This invention relates to wall systems particularly intended for use in sports courts for sports such as racquetball and squash. The wall systems according to this invention may also be used in any other application where dimensional stability as a function of moisture changes is important. Other uses include walls for buildings (both interior and exterior walls), trailers, railroad cars, and the like.
In view of the rapid growth of racquet sports such as racquetball and squash, a great deal of emphasis is being placed on the development of an economical and satisfactory wall system suitable for these sports. The major types of wall systems now in use fall into primary categories: plaster walls, where various types of plaster are applied over a masonry receiving surface, and panel walls, where wood based panels are applied over steel studs.
Plaster over masonry walls have proven unsatisfactory because of settlement and shrinkage cracks, high cost, surface condensation (sweating) during periods of high humidity, cutting of the plaster caused by racquet impacts on side walls, spalling on front impact walls caused by ball impact and suction as the ball leaves the wall, long drying times required after plaster application which delay the openings of the facilities, difficulty of obtaining adequate on-the-job quality control with reference to mix ratios and application techniques, and the great difficulty of getting paints or coatings to permanently bond to the plaster. As a result, plaster walls are costly to install and are very costly to maintain in good condition. Also, there is an appreciable amount of lost revenue resulting from shut downs required to make repairs.
Walls comprising wood based panels over steel studs have solved most of the problems associated with plaster systems by concealing settlement cracks, substantially reducing surface condensation, resisting cutting by racquets on side walls, easily withstanding spalling of front impact walls from shock and suction, requiring no drying time, requiring very little on-the-job quality control supervision, and having an excellent ability to hold paint surface coatings and coverings such as melamine. The problems which are normally related to the use of wood based panels stem from the fact that the panels absorb varying degrees of moisture, resulting in shrinkage and expansion forces within the panels. The forces generated by the changes in moisture content in the panels cause shrinkage cracks, warpage of the panels, and buckling of the panels, normally at the seams and particularly in vertical seams. Shrinkage cracks are unsightly, and warpage and buckling of the panels at the seams destroy the planarity of the panels and render the wall surfaces unsightly and unplayable.
Attempts have been made to minimize this inherent movement potential of wood based panels due to changes in moisture content by introducing air conditioning, by increasing court ventilation to approximately eight air changes per hour, by using panels which have an appreciably higher density at a much higher cost than those which are normally available, and by coating the panels with various thicknesses of melamine facing materials which also substantially increases cost. None of these approaches have proven entirely satisfactory in practice since inefficient air conditioning and ventilation in sports courts are the rule, rather than the exception. Also, the perspiration given off by active players serve to appreciably increase the relative humidity in the courts, a factor which contributes to the unwanted growth of the wood based panels. Frequently it is necessary to install the panels in the building before the air conditioning is turned on and when there are significant amounts of construction moisture still in the air. Lastly, air conditioning, ventilation, the use of high density wood based panels to retard the rate of moisture absorption rather than lower density panels (62 pcf rather than 45 pcf), and the use of expensive melamine surfacing materials on both the fronts and backs of panels all serve to very substantially increase the cost of construction and operation of the courts.
The present invention is based on the observation that the use of wood based panels has advantages which greatly outweigh the known disadvantages. The present invention directs itself to overcoming the lack of dimensional stability normally associated with wood based panels by controlling their normal shrinkage and growth characteristics in a positive and relatively inexpensive manner. Lower density panels (45 pcf) and paint finishes can be used in the wall system according to the present invention.